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中国物理学会期刊

可调自旋-轨道耦合玻色-爱因斯坦凝聚体的隧穿动力学

CSTR: 32037.14.aps.71.20220697

Tunneling dynamics of tunable spin-orbit coupled Bose-Einstein condensates

CSTR: 32037.14.aps.71.20220697
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  • 研究了在周期驱动拉曼耦合下的可调自旋-轨道耦合玻色-爱因斯坦凝聚体的能带结构、非线性朗道-齐纳隧穿动力学以及隧穿率. 利用高频近似得到了与时间无关的Floquet哈密顿量, 发现周期驱动可以有效地调控自旋-轨道耦合和非线性相互作用. 与两能级模型对比, 解析地得到了能带出现loop的临界条件以及loop的宽度. 研究发现, 当种内原子间相互作用等于种间原子间相互作用时, 不出现loop结构. 而当种内原子间相互作用小于(大于)种间原子间相互作用时, loop出现在下(上)能带. 此时, 自旋-轨道耦合和拉曼耦合都会抑制loop的出现. 特别地, 通过调节外部驱动能控制能带出现loop结构的临界条件. 还研究了可调自旋-轨道耦合玻色-爱因斯坦凝聚体的隧穿动力学. 通过调节周期驱动强度可以调控系统的隧穿动力学, 控制在动量空间发生非线性朗道-齐纳隧穿的位置, 并使系统的自旋组分发生翻转. 最后计算了系统的朗道-齐纳隧穿率, 研究表明周期驱动能够有效调控系统的隧穿率.

     

    We theoretically study the band structure, tunneling dynamics, and tunneling probability of tunable spin-orbit-coupled Bose-Einstein condensates under the periodic driving of Raman coupling. The time-independent Floquet Hamiltonian is obtained in the high-frequency approximation. It is found that the periodic driving can effectively tune spin-orbit coupling and nonlinear interaction. The system is mapped to a standard nonlinear two-level model, and the critical condition for the appearance of the loop in energy band structure and the width of the loop are obtained analytically. When the interspecies atomic interaction is equal to the intraspecies atomic interaction, there is no loop. However, when the intraspecies atomic interaction is smaller (larger) than the interspecies atomic interaction, the loop appears in the lower (upper) energy band. In this case, both spin-orbit coupling and Raman coupling will suppress the appearance of loop. In particular, the critical condition for the appearance of loop structure can be controlled by adjusting external driving. We also study the tunneling dynamics of Bose-Einstein condensate with tunable spin-orbit coupling. More importantly, by tuning the periodic driving, the tunneling dynamics of the system and the location of nonlinear Landau-Zener tunneling can be controlled. We also find that the spin components of the system can be reversed. Finally, the Landau-Zener tunneling probability of the system is calculated. The research shows that the periodic driving can effectively change the tunneling probability of the system.

     

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